tinypy is a minimalist implementation of Python in
64k of code. It includes a parser and bytecode
compiler written in python. tinypy runs on its own
C-based virtual machine with garbage collection.
It supports a fairly decent subset of Python,
including classes with single inheritance,
functions with variable or keyword arguments,
strings, lists, dicts, numbers, modules, list
comprehensions, exceptions with full traceback,
some builtins, and several modules.

libLAS is a C++ library implementing the ASPRS LAS
Format Specification. The library provides an API
for reading and writing LiDAR data stored in LAS
files. There are C, C++, .NET, and Python APIs, as
well as a set of command line utilities for
processing LAS files.

ODB (also known as "spugdb" due to a name clash on code.google.com) is a pure Python key-value style database system. It supports nested transactions, object schemas, cursors, and a simple, X-Path like query language.

dramatis is an actor library for dynamic languages
like Ruby and Python. It allows developers to
create concurrent programs in these languages
using the actor model rather than having to use
low-level threads.

Doapfiend is a command line client and Python
library for fetching, displaying, and manipulating
DOAP (Description of a Project) RDF files.
Doapfiend uses rdflib with RDFAlchemy as an ORM to
query and create DOAP.

xpython is a bundle that includes the Python interpreter and runtime and a number of libraries. It can be compiled into a single binary, thus simplifying software distributions without proper package management. The binary contains Python, wxWindows, SQLite, and a number of useful modules.

pythonOCC is a 3D CAD/PLM development library for the Python programming language. It provides 3D hybrid modeling, data exchange (support for the STEP/IGES file format), GUI management support (wxPython, PyQt, python-xlib), parametric modeling, and advanced meshing features. pythonOCC is built upon the OpenCASCADE 3D modeling kernel and the salomegeom and salomesmesh packages. Some high level packages (for parametric modeling, topology, data exchange, webservices, etc.) extend the builtin features of those libraries to enable highly dynamic and modular programming of any CAD application.